In a semiconductor manufacturing process, high miniaturization of a circuit pattern to be formed on a wafer has been developed, and a process monitoring operation for monitoring whether or not a pattern is formed in the same manner as designed has become more and more important. For example, in order to detect occurrence of a failure or defect in the semiconductor manufacturing process in an early stage or beforehand, measuring and inspecting processes are carried out on a wafer circuit pattern or the like, upon completion of each of the manufacturing processes.
At the time of the above-mentioned measurements or inspections, in a measuring/inspecting method in a measurement and inspection device such as a SEM or the like and a corresponding measuring/inspection method, an electron beam (referred to also as electron ray, electron probe or the like) is irradiated onto a sample such as a wafer while being scanned, and energy such as secondary electrons or the like thus generated is detected. Then, based upon the detection, an image, such as a measured image, an inspection image or the like, is generated by a signal processing, image processing or the like, and based upon the corresponding image, measurements and inspections are carried out.
For example, in the case of an inspection device and an inspection function for carrying out a defect inspection on a circuit pattern, by using an inspection image, images of similar circuit patterns are mutually compared, and a portion having a large difference between them is determined and detected as a defect. Moreover, in the case of a measuring device and a measuring function for carrying out measurements on a circuit pattern, since the amount of generation of secondary electrons or the like fluctuates depending on a surface shape such as irregularities or the like of a sample, based upon evaluation processes of a signal of the secondary electrons, fluctuations or the like of the surface shape of the sample can be confirmed. In particular, by utilizing the fact that the signal of secondary electrons abruptly rises or falls at an edge portion of a circuit pattern, the edge position within a circuit pattern image of the corresponding circuit pattern is estimated so that the dimension value or the like of the circuit pattern can be measured. Then, based upon the measuring results, the quality of the pattern processing of the corresponding circuit pattern can be evaluated.
As the prior art example relating to the above-mentioned measurement and inspection, Japanese Patent Application Laid-Open Publication No. 2006-93251 (Patent Document 1), Japanese Patent Application Laid-Open Publication No. H07-326314 (Patent Document 2), Japanese Patent Application Laid-Open Publication No. 2009-32445 (Patent Document 3) and the like are exemplified. Patent Documents 1 to 3 disclose structural examples of a measurement and inspection device of the SEM system.
Patent Document 1 discloses a technique or the like for measuring a pattern dimension at a desired position on the cross-sectional shape of a pattern. In Patent Document 1, “a dimension measuring method and its device” are proposed in which “by using a scanning-type electron microscope, a secondary electron image of a sample is acquired, an image profile of a pattern for use in measuring a dimension in this acquired secondary electron image is formed by using the secondary electron image, and a model profile, which is most coincident with an image profile formed among a plurality of model profiles corresponding to a plurality of patterns obtained from respective secondary electron images of a plurality of patterns having known cross-sectional shapes and dimensions and having different shapes that have been preliminarily stored, is retrieved, and by using information of the model profile obtained by this retrieval, a pattern dimension is found.”
Patent Document 2 discloses “in a scanning charged particle beam device for irradiating an insulating object or a semiconductor sample with a primary charged particle beam and for detecting a signal obtained from the sample, such a scanning charged particle beam device as to remarkably reduce an electrification phenomenon of the sample can be realized”, etc.
Patent Document 3 discloses objects or the like, such as “to provide an inspection device and an inspection method using a scanning electron microscope that can detect an electron beam image with high precision and also eliminate the limitation of an AD conversion element relating to a low sampling rate that causes a problem at the time of detection.” Moreover, with respect to the objects, for example, a method is proposed in which “for each of N-number of continuous digital values included in the sampling signal, the N-number of digital values are successively added to generate a digital luminance signal having a 1/N frequency of the sampling frequency.”